What does the illuminated "!" mean? on 2008 Mazda MAZDASPEED3

When driving to work this morning, the "!" came on and stayed on for 5 minutes, lasting the duration of my morning commute. What does this mean? It was cold, and I didn't give my car time to warm up.
I'm looking at purchasing this car from Carmax and have an appt this afternoon at the Mazda dealership for a complete car inspection.